Investigating Production Planning and Scheduling Approaches in Sawmill Operations

Abstract

This thesis addresses production planning and scheduling in sawmill operations, which involve a unique production flow characterized by both divergence and convergence. The study is conducted in collaboration with Södra Skogsägarna ekonomisk förening. Its objective is to identify existing production planning and scheduling approaches from the academic literature and to select the most suitable approach based on performance measurement.

The study employs an operations research framework that began with defining the problem. Next, it established a framework for existing production planning and scheduling approaches relevant to sawmill processes. Then, a simulation model is developed to analyze production performance for the selected planning and scheduling approach. Four different scenarios were created, each reflecting various decoupling point positions.

The findings of this thesis apply to sawmill operations in general. The first key finding identifies the existing production planning and scheduling approaches in sawmill production, which can be classified into integrated and decomposition techniques. Based on an analysis of the benefits and drawbacks of each approach, the agent-based planning and scheduling method is chosen for its ability to break down complex problems into smaller sub-problems, thereby reducing computational complexity. Among the coordination mechanisms for agent-based planning and scheduling, the hybrid push-pull method with a decoupling point is chosen due to its suitability in reflecting the operational characteristics of the sawmill production system. The second key finding involves analyzing the impact of various decoupling points on performance measurement. This study specifically focused on how these decoupling positions affect average inventory levels. The decoupling positions are placed between three stages in the sawmill process: sawing, drying, and after-treatment. The results indicate that placing the decoupling point before the after-treatment stage yields the best performance regarding average inventory levels. This configuration employs two distinct production strategies: a push strategy before the decoupling point and a pull strategy afterward. The push strategy allows the agents to push the logs without considering demand, while the agent after the decoupling point processes the product according to customer demand. Placing the decoupling point before after-treatment enables higher average inventory levels, providing greater production flexibility by making more inventory available to adapt to varying customer demands.

Popular Abstract

Balancing efficiency and flexibility is a major challenge in a sawmill production system. Producing too much creates unnecessary inventory, while producing too little makes it difficult to respond quickly to customer needs.
Imagine baking cookies from one batch of dough. From the same dough, you can make large, small, round, or rectangular cookies. However, different cookies may require different baking times, meaning they cannot always be baked together without affecting quality.

A sawmill works in a very similar way. From one log, many products can be created, such as boards of different dimensions. At the same time, these products pass through several production stages that must be carefully coordinated. This combination creates both divergent and convergent production flows, making production planning in sawmills especially challenging.
How should a sawmill decide what to produce and when to produce it? Producing too much can lead to large inventories and quality degradation, while producing too little can make it difficult to fulfil customer demand. Finding the right balance is therefore essential.

This study investigated different production planning and scheduling approaches for sawmills. The focus was on the position of the decoupling point, where production shifts between push and pull strategies. A push strategy means products are produced before customer demand is known, while a pull strategy means production is based on actual customer orders.

To analyze this, a simulation model of the sawmill process was developed, including sawing, drying, and after-treatment stages. Four scenarios with different decoupling-point positions were tested.
The results showed that combining push and pull strategies is beneficial for sawmills because of their unique production characteristics. The best performance was achieved when the decoupling point was placed before the after-treatment stage. In this setup, the earlier production stages use a push strategy to maintain production flow, while the later stages apply a pull strategy to adapt to customer demand.

This combination improves production flexibility while reducing unnecessary inventory buildup and quality degradation. The findings from this study can therefore support sawmill companies in making better decisions regarding production strategy and inventory placement. By balancing push and pull production strategies, companies can improve efficiency, reduce waste, maintain product quality, and better respond to customer demand.

• author: Ramadhanti, Zavira and Wu, Haoyang
• supervisor: Danja Sonntag
• organization: Department of Industrial and Mechanical Sciences; Production Management
• course: MIOM01 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Production planning and scheduling, divergent production flow, convergent production flow, agent-based planning, simulation, decoupling points, sawmill planning
• other publication id: 26/5334
• language: English
• id: 9229086
• date added to LUP: 2026-05-29 17:02:36
• date last changed: 2026-05-29 17:02:36